Oh yeah, you have a great point. But if a real store is bad it will probably vanish by itself. Here, if you let people spam without doing anything, they will keep on spamming.
Flags are worthless if there's no one abusing the reward pool but as long as evil stuff happen, (that may be forever) flags will be needed.
If a store is taking advantage of people by scamming them someone has to shut it down if not, it will keep on scamming.
I would love if there would be no need for flags but they are designed with a reason. To shut down the store. ;)